1. Field of Invention
This invention relates, in general, to electric powered vehicles, and more specifically, to electric powered vehicles which utilize the solar energy to generate the energy required for propulsion and other uses such as powering a transistorized radio or a audio cassette recorder, etcetera.
2. Description of the Prior Art
With the decline in the fossil fuel reserves and increasing industrialization of majority of the countries throughout the world, the use of alternate sources of energy has become an urgent task. Secondly, many countries are facing traffic jams in their urban areas which have devastating effects on the health of the drivers of fossil fuel powered vehicles and also, those of the residents of those areas. This has lead to the search for the electricity powered vehicles which would not emit pollutants. The pollution problem is very severe in many of the under-developed countries where a large number of two cylinder vehicles such as scooters, three-wheelers, and motor-cycles are used in large numbers. Many of these two cylinder engines burn lubricating oil, in addition to gasoline, resulting in many of the respiratory diseases.
In electric powered engines, the motion is provided using electric motors and speed reduction is done using a train of sprockets connected by chains, or by a gear train. The energy loss in such transmissions is minimal. The efficiency of the electric motor driven system is far more than those of any, driven by the internal combustion engines.
The energy stored in a fossil fuel per unit volume is far greater than that of the corresponding volume of batteries which store electrical energy. Considering the specific weights (considering the weight as the criteria for energy or fuel consumption) of these two types of storages, the energy stored in a gasoline tank is far in excess of those of the batteries. This has been the primary reason the fossil fuel powered vehicles are in use today even though, efficiency-wise, they are far less energy efficient. A number of these vehicles are not weight optimized based on the number of passengers they carry, including speed considerations.
In summary, the fossil fuel based vehicles are undesirable because of several reasons: The first one is that they are heavy therefore energy inefficient. The second is that the world fuel supply is limited and declining . The third is that many countries do not have these fuel reserves and are short of hard currency to purchase the fuel in the international markets. Finally, these vehicles are polluting, and the time has come that people have become aware of the diseases caused by pollutants emitted by these vehicles.
In the design of electric vehicles which are available to-day, attempts have been made to reduce the weight of the structure to some extent but in many cases, the existing body remains as it used to be. Thus, such vehicles need large number of batteries (high energy storage), which (the batteries) by themselves are quite heavy to power such vehicles. If we look at the combined weight of the vehicle and the batteries, there is not much progress, as far as the reduction in weight is concerned. This has resulted in not much improvement in the energy efficiency.
One of the problems with the batteries is that their charge holding capacity goes down very significantly as the temperature decreases say from 20.degree. C. (centigrade) to the freezing point of water (0.degree. C.). Thus, these electric vehicles have very limited range (driving distance between two charges).
Thirdly, in many under-developed countries the supply of electricity in different areas is not continuous; there are frequent power break-downs or there are planned shut downs (rationing). In such places, the design of the electric vehicles has to be based on reduced dependence on city supply but increased utilization of other means of charging the batteries, which can be due to the use of solar energy.
The use of solar energy is also very important in countries such as USA or Canada because, by varying the ratio of the solar energy to that of the city supplied electrical energy, one can increase the driving distance (the range) before the batteries need to be re-charged.
As stated before, by minimizing the weight of the structure, one can increase the range of the vehicle before it needs re-charging. Since there is approximately a maximum of 800 Watts per square metre of solar energy available anywhere in the world, if those vehicles whose weights, including the passengers weights, are such that the energy available after conversion (conversion efficiency of approximately 13% for photovoltaic panels) of the above mentioned energy (800 Watts/meter.sup.2) over a whole day is significant part of the daily energy consumption then, one can easily meet the objectives of non pollution and fossil fuel conservation. In many areas of the world, especially in smaller cities, the solar energy available in the electrical form (after conversion), can be sufficient. In other places, a combination of city supplied electrical energy and the solar energy will take care of the energy needs. In this way, one can avoid the combustion of fossil fuels in the vehicles used for transportation.